Process of producing a pigment



Patented Dec. 9, 1930 omen sm'r'es DAVID V. AULT, OF MORTON, PENNSYLVANIA PROCESS OF PRODUCING A PIGMENT No Drawing. Application filed February My invention relates to an improved pigment, and to the process of preparation thereof.

I have discovered that a gray, clay-like ore, deposits of which are located in the valley of the township of Manheim, county of York, State of Pennsylvania, and more par-v ticularly in a certain parcel or tract of land deeded to me by "Lydia M. Baugher and recorded in York County, said tract or parcel being bounded as'follows: On the east, by a public road running from Lineboro to the road leading from Glenville'to Black Rock; on thesouth by lands of the Baltimore branch of the Western Maryland Railway Company; on the west by land of Lydia M.Baugher; and on the north by a public road leading from Glenville toBlack. Rock, may be subjected to suitable steps of treatment in order to yieldasubstantiallypure and naturally occurringveryfinely divided sericite capablefof being satisfactorily and, economically produced and suitable for use as a pigment'in the manufacture of paint, rubber and the like. The ore in connection with which I conceived the possibility of developing a pigment is a dark, clay-like substance, naturally moist and capableof easily giving a dark gray smudge when rubbed. While this ore, atle'ast that I '30 with which I am familiar, contains a: large portion .of very finely divided sericite, yet refinement of the ore is necessary in order to obtain sericite in a finely divided form-and suitable for incorporation as a base in a suitable vehicle. At first, I sifted or screened the ore and obtained a product which wasincorporated as a base in oil. The paint, so prepared, while capable of standing up under fairly severe acid and alkali conditions, was, 40 nevertheless, objectionable on account of particles of foreign matter giving asomewhat gritty appearance and interfering with easy application and also on account of physical properties in general inferior to those obtained by the finally developed process hereinafter referred to. I next ground the ore so that all of it was reduced to a very fine powder; and, While this: gave a satisfactory base, it was objectionable on account of discolorations', limited range of 4, 1929. Serial 110,337,528.

colors, and lack of purityiand the best physical properties. i

The process, as finally developed mans nowpracticed, results in the obtaining of relatively pure sericite very finely divided and of a gray color. To this end, the ore, as mined, is first heated to drive ofi moisture; the dried ore is then screened in order to remove particles of foreign matter; and the screened material is then subjected to air separation. This series of steps applied to the ore results in the production of a substantially pure finely divided sericite and one having the desired physical properties as a coating material or base in a high degreevery much higher than obtained by my prior method referred to. The division is so fine that all of the sericite is capable of passing through a QOO-mesh screen and a large portion may be passed through a LOO-mcshscreen; the particles, though quite fine, vary in fineness so that voids in a paint contain ing this pigment are minimized.

The fact that the ore, as mined, with or without the removal of coarse particles of'i foreign matter by siftingy may be ground in any suitable mill shows that it is different from mica for the grinding of mica, owing to its crystalline laminated character, is difficult. While mica is classified as soft material, it is one of the most difficult to grind due to its flexible, smooth surfaces, and lack of brittleness. It cannot be crushed but must go shredded, torn and split. VVhenground y, and flakey; and such grinding must be done by ahammer mill. To obtain finer grinding, the process of Wet grinding has been used, this process usually involving placing a suitable amount of cleaned mica in water in a receptacle and subjecting the material to agitation in order to secure grinding by rubbing of the pieces or particles of mica upon one another. The wet process is necessarily slow and expensive. On the other hand, by subjecting the ore with which I am dealing to the aforesaid steps or treatment, I am able to obtain a substantially pure pigment and one which is more finely divided and of graduated fineness and more suitable for incorthe ground material is somewhat coarse All ' poration as a base pigment in a vehicle than ground mica. I I k f I' produce a sericite which is so finely d1- vided, of such a state of purity and of such specific gravity that it may be incorporated satisfactorily 'in'a vehicle merelyby agitas ftion. While, I may grind my material into the vehicle, this is not necessary. nlsogmy improved pigment produces a superior color,

jaoidity' or'alkalinity, without dangerofsaponification or other chemical action. Boilin'g. acid or alkaline solutions are Without efiect on paint having thepigment; there is no reaction of the pigment to H O, CO S0 or H S;it has noefi'ect on: Vehicle oils-nor the oxidized prod icts thereof; and it provides without decompositionr Not onlydoestlie a stable coating; .After being {heated-to 2000 degrees Fa I find that the material remains'inert; .It fuses at a hightemperature pi ment have-these desirable properties, but

' ing chemical analysis :4

' of muscovite, one of the families '0 After subjecting the ,ore to the steps, of

' Tracejs' of magnesiaand lime. This refined material has been authoritative- ,p

it as good hiding andbulking power.

treatment already referred to, the resulting roduct is a definite chemical compound. It

13 a sericite having substantially the follow- 1 determined to besericite. a secondary form mica.

abovedanalysis applies only tothe' 'ore'fwith which, I am i dealing.- There may befother I micaceousores; containingavery [finely [divided mica constituent which. may beseption steps in orderto. produceja'f purefinely is". the pigment and heat 1 resistant, but. it has good electrical fcharacteristics, It isfa good insulator; it has high.

dielectric properties;-and it preventselecf trolysis of metalworl; with whichitisused.

'. The coating prevents contact of moisture'with metal; it prevents the; formation of an electrolyte and consequent rusting; and, as the base is inert," no chemical action can take.

place between itland' the vehicle or with the metal covered by thepaint, In this connec- "tion,'-i f a color other than the natural gray one is desired on metal,=I prefer to apply a prim pign'ientsj to prof-w a I findthatthe .naturall in separating the naturally-occurring sericite ing'coat including the sericite base without a color pigment and then to apply color coats on the neutral or-inert priming coat, as, in this way, the metal is separated from the to .coat or coats by the inert priming coat an possible chemicalor electrolytic action is upon by strong acid or alkalies and it en-. dures very high temperatures. Y

. As already pointedout, the treatment steps,

of drying, screening and air'separation are highly important in order to secure a very fine material and one which may be used as a pigment to provide a paint which has a gray ior neutral color towhich color, pigmentsemay be added to give a wide range of colors. When the refined sericite pigmentis incorporated inla suitable vehicle a gray and opaque paint results, one having the; deslrable.

physical properties already mentioned, and

onewhich may have its colorchanged bythe addition of suitable color pigments. For example,a,light gray may be had by theadditionofzinc oxide; green, by-the addition of.

green; and red,' .by the addition ,of

chrome oxideofn-on, c i nd finedfinely divided sericilie'pigment may be incorporatediwith a vehicle merely by agitation and. without grinding. .Sucha pigment has greater coveringfor; bulking power: than pigments with v which. I I am familiar;

for exam le, itreguires five times as much, by weight o redlea Also, after incorporation of my. mproved igment ina suitable ve- Chinawood oil may, e added to the linseed oil in order, to produce atough, water-shedmayor. the vehicle oil whereupon av mixture maybe. readily eflected. Any suitable driers .may be .emplo ed, forv example, imagne'sium -dioxideand lit arge, are satisfactory. Where hicle,1there is relatively less settling out when compared with other bases. v Any suitable ve .hiclemay' be employed; For ordinary; coat- 1 ings,;;the vehiclema consist of linseed oil.

. a dingelasticfilm. Cumar. gum, or c'umarone, V I "is to eunders o m c t th finaybe iaddedto th oiljto givemsistanceto .,acid, alkalis, and water; and, in order that the gum may beisatis'factorily incorporated; I dissolvev item ,a suitable petroleum spirit to zh fe ucethergravityjthereof tosubstantially arated by; Sub ecting the ore to the pur1fica 5o ividedmicaproduct suitableforuse a 'pigment. H

' -.Not only high temperatures are encountered, soya oil i may be substituted for linseedoil.

. From the foregoing, it will be apparent;

that I produce a pigment by subjectingjore of, the character referred to to a mode of treatment consisting in drying the ore and ment' from a-clay-like material containin sericite' in. a naturally-occurring, finely-d1- vided condition which consists in drying such material and in separating the finely-divided sericite from gritty particles.

:2. The process of manufacturing a pigment from a clay-like material containing sericite in a naturally-occurring, finely-divided condition which consists in heating the material to dry it, in screening the material, and in separating the finely-divided sericite therefrom.

3. The process of manufacturing a pigment from a clay-like material containing sericite in a naturally occurring, finely-divided condition which consists in providing such material in a dry state and in removing the finely-divided sericite from foreign matter by air separation.

4. The process of manufacturing a pig-' ment from a clay-like material containing sericite in a naturally-occurring finely-divided condition which consists in heating the material to dry it, in screening the material, and inremoving the finelydivided sericite from foreign matter by air separation.

In testimony whereof I aflix my signature.

DAVID v. AULT. 

